This is nearly trivial.

WARNING: Untested code ahead! Initialization, etc not included.

The 100Khz signal can be generated by code that toggles a GPIO every 5th
instruction time. Code the 50Hz signal is then interspersed around it:

 CBLOCK 0x??
    count
 ENDC

OUT100K = 0            ; GPIO pin assignments
OUT50  = 1

; Each iteration of the following main_loop takes 50uSec
; and generates 5 full cycles of the 100KHz signal.
; Since the state of the 50Hz signal should change every 0.01
; second, we want to change the state of the 50Hz output each:
;        0.01Sec  /  50uSec = 200th time around the loop

    movlw    .200
    movwf    count

main_loop:
    bsf    GPIO,OUT100K        ;[1:1]
    movlw    1 << OUT50         ;[1:2] assume it is time to toggle
    movf       count,F                 ;[1:3] time to toggle?
    skpnz                                   ;[1:4] skip if not
    xorwf     GPIO,F                 ;[1:5] toggle the pin now

    bcf    GPIO,OUT100K        ;[1:6]
    movlw    .200                       ;[1:7] assume it is time to reset
count
    movf       count,F                  ;[1:8] time to reset?
    skpnz                                   ;[1:9] skip if not
    movwf    count                     ;1:10] reset count

    bsf    GPIO,OUT100K        ;[2:1]
    decf    count,F                      ;[2:2] decrement count
    nop

    bcf    GPIO,OUT100K        ;[2:6]
    goto    $+2
    goto    $+2

    bsf    GPIO,OUT100K        ;[3:1]
    goto    $+2
    goto    $+2

    bcf    GPIOI,OUT100K        ;[3:6]
    goto    $+2
    goto    $+2

    bsf    GPIO,OUT100K        ;[4:1]
    goto    $+2
    goto    $+2

    bcf    GPIOI,OUT100K        ;[4:6]
    goto    $+2
    goto    $+2

    bsf    GPIO,OUT100K        ;[5:1]
    goto    $+2
    goto    $+2

    bcf    GPIO,OUT100K       ;[5:6]
    goto    $+1                ;[5:7-8]
    goto    main_loop       ;[5:9-10]


Bob Ammerman
RAm Systems





----- Original Message -----
From: "Lasse Madsen" <Lasse.madsen@ELEKTRONIK.DK>
To: <PICLIST@MITVMA.MIT.EDU>
Sent: Sunday, March 17, 2002 12:29 PM
Subject: [PIC]: 2 oscillators in one pic ?


Hi all

I was wondering if its possible to make 2 oscillators running in one pic at
the same time ?
the PIC is a 12C50x with external 4MHz crystal and oscillators should be on
100KHz and 50Hz.

Output on any availble GPIO pin is ok ...

I personally doubt it can be done because i dont think a pic can multitask
but maby im wrong (i hope so)

Best regards
Lasse Madsen

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